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Competing Interests: We declare no competing interests.

Hypersensitivity pneumonitis (HP) is a rare disease in childhood with the prevalence of 4 cases per 1 million children and an incidence of 2 cases per year. The average age of diagnosis at pediatric age is approximately 10 years. The pathogenesis of HP is characterized by an immunological reaction caused by recurrent exposure to triggering environmental agents (mostly bird antigens in children). The clinical picture of HP is complex and variable in children, often presenting in subacute forms with cough and exertion dyspnea. A diagnosis of HP should be considered in patients with an identified exposure to a triggering antigen, respiratory symptoms, and radiologic signs of interstitial lung disease. Blood tests and pulmonary function tests (PFT) support the diagnosis. Bronchoscopy (with bronchoalveolar lavage and tissue biopsy) may be needed in unclear cases. Antigen provocation test is rarely required. Of note, the persistence of symptoms despite various treatment regimens may support HP diagnosis. The avoidance of single/multiple triggers is crucial for effective treatment. No evidence- based guidelines for treatment are available; in particular, the role of systemic glucocorticoids in children is unclear. With adequate antigen avoidance, the prognosis in children with HP is generally favorable., (© 2022. The Author(s).)

Background: Anxiety and depression may affect asthma control. Previously, it has been reported that the hospital anxiety depression scale (HADS) questionnaire was fruitful in the management of adolescents with asthma. This study compared the scores of two different questionnaires, namely the Childhood Anxiety Sensitivity Index (CASI) and Children's Depression Inventory (CDI), with asthma control level and lung function in asthmatic adolescents, evaluated in a real-life setting., Methods: A group of adolescents with asthma was consecutively enrolled. Asthma was diagnosed according to the GINA document, and consistently the symptom control grade was assessed. The adolescents completed the CASI, CDI, and Asthma Control Test (ACT) questionnaires. Visual Analogue Scale (VAS) for asthma symptoms perception and doctor's asthma control evaluation were considered. Lung function and clinical characteristics were also assessed., Results: Totally, 87 asthmatic adolescents (60 males, 27 females, median age 14.2 years) were evaluated. 16.1% of asthmatic adolescents had anxious symptoms detected by CASI, and 11.5% depressive symptoms revealed by CDI. High scores of both CASI and CDI were significantly associated with uncontrolled asthma (p= 0.013 and 0.043, respectively)., Conclusions: This study showed that anxiety and depression affected asthma control. Thus, in clinical practice, the psychological assessment could be included in asthmatic adolescents' asthma work-up.

The antibody profile against autoantigens previously associated with autoimmune diseases and other human proteins in patients with COVID-19 or multisystem inflammatory syndrome in children (MIS-C) remains poorly defined. Here we show that 30% of adults with COVID-19 had autoantibodies against the lung antigen KCNRG, and 34% had antibodies to the SLE-associated Smith-D3 protein. Children with COVID-19 rarely had autoantibodies; one of 59 children had GAD65 autoantibodies associated with acute onset of insulin-dependent diabetes. While autoantibodies associated with SLE/Sjögren's syndrome (Ro52, Ro60, and La) and/or autoimmune gastritis (gastric ATPase) were detected in 74% (40/54) of MIS-C patients, further analysis of these patients and of children with Kawasaki disease (KD), showed that the administration of intravenous immunoglobulin (IVIG) was largely responsible for detection of these autoantibodies in both groups of patients. Monitoring in vivo decay of the autoantibodies in MIS-C children showed that the IVIG-derived Ro52, Ro60, and La autoantibodies declined to undetectable levels by 45-60 days, but gastric ATPase autoantibodies declined more slowly requiring >100 days until undetectable. Further testing of IgG and/or IgA antibodies against a subset of potential targets identified by published autoantigen array studies of MIS-C failed to detect autoantibodies against most (16/18) of these proteins in patients with MIS-C who had not received IVIG. However, Troponin C2 and KLHL12 autoantibodies were detected in 2 of 20 and 1 of 20 patients with MIS-C, respectively. Overall, these results suggest that IVIG therapy may be a confounding factor in autoantibody measurements in MIS-C and that antibodies against antigens associated with autoimmune diseases or other human proteins are uncommon in MIS-C., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Burbelo, Castagnoli, Shimizu, Delmonte, Dobbs, Discepolo, Lo Vecchio, Guarino, Licciardi, Ramenghi, Rey-Jurado, Vial, Marseglia, Licari, Montagna, Rossi, Montealegre Sanchez, Barron, Warner, Chiorini, Espinosa, Noguera, Dropulic, Truong, Gerstbacher, Mató, Kanegaye, Tremoulet, Pediatric Emergency Medicine Kawasaki Group, Eisenstein, Su, Imberti, Poli, Burns, Notarangelo and Cohen.)

Background: Development of a diverse T-cell receptor β (TRB) repertoire is associated with immune recovery following hematopoietic cell transplantation (HCT) for severe combined immunodeficiency (SCID). High-throughput sequencing of the TRB repertoire allows evaluation of clonotype dynamics during immune reconstitution., Objectives: We investigated whether longitudinal analysis of the TRB repertoire would accurately describe T-cell receptor diversity and illustrate the quality of T-cell reconstitution following HCT or gene therapy for SCID., Methods: We used high-throughput sequencing to study composition and diversity of the TRB repertoire in 27 infants with SCID at 3, 6, and 12 months and yearly posttreatment(s). Total RNA from peripheral blood was used as template to amplify TRB rearrangements., Results: TRB sequence analysis showed poor diversity at 3 months, followed by significant improvement by 6 months after cellular therapies. Kinetics of development of TRB diversity were similar in patients with a range of underlying gene defects. However, in patients with RAG and DCLRE1C defects, HCT with no conditioning or immune suppression only resulted in lower diversity than did HCT with conditioning. HCT from a matched donor correlated with higher diversity than did HCT from a mismatched donor. Naive CD4 + T-cell count at 6 months post-HCT correlated with higher TRB diversity. A Shannon index of diversity of 5.2 or lower 3 months after HCT predicted a need for a second intervention., Conclusions: TRB repertoire after hematopoietic cell therapies for SCID provides a quantitative and qualitative measure of diversity of T-cell reconstitution and permits early identification of patients who may require a second intervention., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The management of fish allergy relies on the elimination of all fish from the diet. Nevertheless, an exclusion diet can be problematic from a paediatric nutritional perspective. The issue of a substitute diet for children suffering from fish allergy seems to be not adequately addressed and the consequences of a fish exclusion diet in paediatric age are not known. Fish has an important nutritional value, it is rich in vitamins of group B, D and A, selenium, calcium and phosphorus, iron, zinc, magnesium, iodine and omega-3. While vitamins and iodine are normally present in the diet, omega-3 is present in few other foods, such as vegetable seed oils and nuts. Hence, the scientific research indicates a generic advice regarding a possible omega-3 supplementation in children with fish allergy. Given the knowledge about omega-3 supplementation having a potential good risk-benefit ratio and the absence of serious adverse events related to the omega-3 supplementation, this type of supplementation may seem advisable in children affected by fish allergy.

The complement system plays an essential role in both innate and adaptive immune responses. Any dysregulation in this system can disturb normal host defense and alter inflammatory response leading to both infections and autoimmune diseases. The complement system can be activated through three different pathways. Inherited complement deficiencies have been described for all complement components and their regulators. Despite being rare diseases, complement deficiencies are often severe, with a frequent onset during childhood. We provide an overview of clinical disorders related to these disorders and describe current diagnostic strategies required for their comprehensive characterization and management., (© 2022 The Authors. Pediatric Allergy and Immunology published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Inborn errors of immunity (IEI), also referred to as primary immunodeficiencies (PID), are disorders that, for the most part, result from mutations in genes involved in immune host defense and immune regulation. With the increased availability of high-throughput DNA sequencing and improved genomic data interpretation, the number of newly identified genes associated with IEI has exponentially increased over the last decade. Here, we focus on the newly described IEI associated with severe COVID-19 and SASH3 deficiency, the most recently reported IEI with impaired T-cell receptor (TCR) signaling., (© 2022 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)

Primary atopic disorders (PADs) are monogenic diseases characterized by allergy or atopy-related symptoms as fundamental features. In patients with PADs, primary immune deficiency and immune dysregulation symptoms are usually coexist. Chronic skin disease, manifesting with erythroderma, severe atopic dermatitis or eczema, and urticaria, is one of the main features observed in PADs, such as hyper-IgE syndromes, Omenn syndrome, Wiskott-Aldrich syndrome, IPEX-linked syndrome, skin barrier disorders, as well as some autoinflammatory diseases. The recognition of PADs in the context of an allergic phenotype is crucial to ensure prompt diagnosis and appropriate treatment. This article provides an overview of the main PADs with skin involvement., (© 2022 The Authors. Pediatric Allergy and Immunology published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Activated phosphoinositide 3-kinase delta syndrome (APDS) is a recently described form of inborn error of immunity (IEI) caused by heterozygous mutations in PIK3CD or PIK3R1 genes, respectively, encoding leukocyte-restricted catalytic p110δ subunit and the ubiquitously expressed regulatory p85 α subunit of the phosphoinositide 3-kinase δ (PI3Kδ). The first described patients with respiratory infections, hypogammaglobulinemia with normal to elevated IgM serum levels, lymphopenia, and lymphoproliferation. Since the original description, it is becoming evident that the onset of disease may be somewhat variable over time, both in terms of age at presentation and in terms of clinical and immunological complications. In many cases, patients are referred to various specialists such as hematologists, rheumatologists, gastroenterologists, and others, before an immunological evaluation is performed, leading to delay in diagnosis, which negatively affects their prognosis. The significant heterogeneity in the clinical and immunological features affecting APDS patients requires awareness among clinicians since good results with p110δ inhibitors have been reported, certainly ameliorating these patients' quality of life and prognosis., (© 2022 The Authors. Pediatric Allergy and Immunology published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

The diagnosis of drug-induced enterocolitis syndrome (DIES), resembling the typical findings of a well-known disease, the food protein-induced enterocolitis syndrome (FPIES), was acknowledged in the first publication on the topic in 2014. Ten cases of DIES have been described so far. Unanswered questions concerning DIES include its pathogenetic mechanism, natural history, the possible presence of predisposing genetic factors, and the potential existence of its atypical forms. DIES is a recently defined and intriguing clinical entity, similar to FPIES but triggered by drugs. It seems well-defined from the clinical point of view, but its pathogenetic mechanisms are not known. DIES deserves more attention among allergists, especially among the professionals who work with children, and all efforts should be conceived to improve its correct recognition and accurate management., (© 2022 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

The alpha-gal syndrome is an allergic syndrome that comprises two clinical pictures: an immediate hypersensitivity to drugs containing alpha-gal and a delayed hypersensitivity to the ingestion of red mammalian meat. This allergic syndrome is often under-recognized, and patients are mislabeled with diagnosis as spontaneous urticaria or idiopathic anaphylaxis. Even though less frequently, children could also be of interest, especially in tick-endemic areas. In most cases, a positive anamnesis for tick bites months before the onset of symptoms is recorded. The clinical manifestations could range from asymptomatic cases to severe anaphylaxis. The most frequently used diagnostic test is the determination of specific IgE for alpha-gal. Oral provocation test is usually reserved to unclear cases or to verify tolerance after diet. No long-term follow-up studies have been published, although an elimination diet could lead to a decrease of specific IgE for alpha-gal and a possible reintroduction of some avoided foods. This paper provides a literature review, focused on pediatric age, and an evaluation of available diagnostic tests. We analyze the correlation between tick bites and symptom onset and unfold the different clinical pictures to help clinicians to promptly recognized this syndrome. Lastly, we address unmet needs in this specific allergy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Saretta, Giovannini, Mori, Arasi, Liotti, Pecoraro, Barni, Castagnoli, Mastrorilli, Caminiti, Marseglia and Novembre.)

Eosinophilic esophagitis (EoE) is an emerging allergen-mediated disease characterized by symptoms of esophageal dysfunction and eosinophilic inflammation. EoE diagnosis requires 15 eosinophils per high power field (eos/HPF) in tissue biopsies endoscopically obtained. The need for several endoscopies to monitoring the disease and the absence of validated non-invasive biomarkers or tools are the main reasons for the significant burden on affected patients and the healthcare system. There is a critical need for non-invasive or minimally invasive biomarkers. In the last years, several efforts have been made to identify potential biomarkers for diagnosing and monitoring the disease that we summarized in this review. The future of EoE is exciting from both a diagnostic and therapeutic standpoint. Further research is required to confirm phenotypes and histological or serological biomarkers to provide a novel endotype classification based on different cytokine or genetic signatures relevant to precision medicine.

Primary immunodeficiency disorders (PIDs) are rare inherited monogenic disorders of the immune system, characterized by an increased risk of infection, immune dysregulation and malignancies. To date, more than 420 PIDs have been identified. The recent introduction of high throughput sequencing technologies has led to identifying the molecular basis of the underlying aberrant immune pathway, and candidate targets to develop precision treatment, aimed at modifying the clinical course of the disease. In PID, targeted therapies are especially effective to manage immune dysregulation and autoimmunity, also reducing the incidence of side effects compared to conventional treatments, sparing the use of steroids and immunosuppressive drugs. Moreover, in the last years, the approach of conventional treatments such as immunoglobulin replacement therapies has evolved and the indication has expanded to new diseases, leading to individualized strategies to both improve infection control and quality of life.  Similarly, the new advent of gene therapy in selected PIDs has introduced the benefit to correct the immunological defect, reducing at the same time the complications related to the hematopoietic stem cell transplantation. Here, we illustrate the most recent findings on tailored treatments for PIDs.

The first cases of as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been reported in Wuhan, China in December 2019. The World Health Organization declared the global pandemic in March 2020. Coronavirus disease 2019 (COVID-19) showed high rates of mortality in the adult population, whereas a mild course was observed in childhood. Allergic diseases, characterized by a type-2 polarization of the immune system, were considered one of the major risk factor of severe COVID-19. Large amounts of clinical data and expert opinions have been collected since the pandemic outbreak. This review summarizes the latest insights on COVID-19 and allergy.

Hymenoptera stings are generally well-tolerated and usually cause limited local reactions, characterized by self-resolving erythema and edema associated with pain. However, Hymenoptera stings can induce immediate and delayed hypersensitivity reactions. In addition to these manifestations, unusual reactions to Hymenoptera stings have been reported. The latter are defined as unusual because of their atypical characteristics. They may differ from classical hypersensitivity reactions due to the stings' particular localization and the unusual involvement of one or more specific organs. Although unusual reactions to Hymenoptera stings are infrequent, it is essential for clinicians to know the possible related clinical manifestations. Here, we review the available literature and propose a diagnostic and management algorithm. At present, there are no defined guidelines for most of the unusual reactions to Hymenoptera stings, which should be managed in a tailored way according to the specifical clinical manifestations presented by the patients. Further studies are needed to better define these conditions and the underlying pathogenetic mechanisms to improve the diagnostic and therapeutic approach., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer AL declared a shared affiliation, with two of the authors RC and GM to the handling editor at the time of the review., (Copyright © 2021 Castagnoli, Giovannini, Mori, Barni, Pecoraro, Arasi, Saretta, Mastrorilli, Liotti, Caminiti, Sturm, Marseglia and Novembre.)

Eosinophilic esophagitis (EoE) is a chronic clinical-pathologic disease characterized by eosinophilic infiltration of the esophageal epithelium with esophageal dysfunction symptoms.EoE can occur at any age and has different clinical manifestations depending on the age onset.To date, esophago-gastroduodenal endoscopy (EGD) with biopsy is the gold-standard for EoE diagnosis.According to the recent consensus guidelines, proton pump inhibitors, corticosteroids and elimination diets could be a first-line therapy option. The aim of the treatment is clinical and histological remission for preventing long-lasting untreatable fibrosis.A multidisciplinary approach (allergist, gastroenterology, dietitian, and pathologist) is recommended for managing patients affected by EoE, given the complexity of its treatment.This review will provide a practical guide to assist pediatricians treating children with EoE.Moreover, it highlights the unmet needs in diagnosis and treatment that require urgent attention from the scientific community in the aim of improving the management of patients with EoE., (© 2021. The Author(s).)

Background: The "Stay at home" COVID-19 lockdown restriction represented a "real-life experiment" of pollen avoidance for children affected by pollen allergy., Methods: The study retrospectively analyzed all children with a known diagnosis of pollen-allergy asthma who attended the emergency department (ED) for an asthma exacerbations (AE) in the town of Mantua and its province in the period March 09-May 03 of the years 2018, 2019 and 2020., Results: In 2020, 4 (0.7%) children with a known diagnosis of pollen-allergy accessed the ED for an AE. Pediatric access was a total of 20 (0.5%) and 12 (0.3%) in 2018 and 2019 in the same period. The rate of hospitalization was 0 in 2020 versus 3 (15%) and 1 (8.3%) in 2018 and 2019, respectively., Conclusions: The inevitable pollen avoidance during COVID-19 lockdown may have prevented asthma exacerbations in children affected by pollen allergy.

Type-I interferons (IFNs) mediate antiviral activity and have emerged as important immune mediators during coronavirus disease 19 (COVID-19). Several lines of evidence suggest that impaired type-I IFN signaling may predispose to severe COVID-19. However, the pathophysiologic mechanisms that contribute to illness severity remain unclear. In this study, our goal was to gain insight into how type-I IFNs influence outcomes in patients with COVID-19. To achieve this goal, we compared clinical outcomes between 26 patients with neutralizing type-I IFN autoantibodies (AAbs) and 192 patients without AAbs who were hospitalized for COVID-19 at three Italian hospitals. The presence of circulating AAbs to type-I IFNs was associated with an increased risk of admission to the intensive care unit and a delayed time to viral clearance. However, survival was not adversely affected by the presence of type-I IFN AAbs. Our findings provide further support for the role of type-I IFN AAbs in impairing host antiviral defense and promoting the development of critical COVID-19 pneumonia in severe acute respiratory syndrome coronavirus 2-infected individuals., (© 2021 Australian and New Zealand Society for Immunology, Inc. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)

Introduction: The Bruton tyrosine kinase (BTK) regulates B cell and macrophage signaling, development, survival, and activation. Inhibiting BTK has been hypothesized to ameliorate lung injury in patients with severe COVID-19, however clinical outcome data is inconclusive., Objective: To evaluate the clinical outcomes of BTK inhibitors (BTKinibs) in patients with COVID-19., Evidence Review: We searched PubMed, Embase, and Web of Science:Core on December 30, 2020. Clinical studies with at least 5 COVID-19 patients treated with BTKinibs were included. Case reports and reviews were excluded., Findings: 125 articles were identified, 6 of which met inclusion criteria. The most common clinical outcomes measured were oxygen requirements (4/6) and hospitalization rate or duration (3/6). Three studies showed decreased oxygen requirements in patients who started or continued BTKinibs. All three studies that evaluated hospitalization rate or duration found favorable outcomes in those on BTKinibs., Conclusions and Relevance: BTKinib use was associated with decreased oxygen requirements and decreased hospitalization rates and duration., (Published by Elsevier Inc.)

Circulating autoantibodies (auto-Abs) neutralizing high concentrations (10 ng/mL, in plasma diluted 1 to 10) of IFN-α and/or -ω are found in about 10% of patients with critical COVID-19 pneumonia, but not in subjects with asymptomatic infections. We detect auto-Abs neutralizing 100-fold lower, more physiological, concentrations of IFN-α and/or -ω (100 pg/mL, in 1/10 dilutions of plasma) in 13.6% of 3,595 patients with critical COVID-19, including 21% of 374 patients > 80 years, and 6.5% of 522 patients with severe COVID-19. These antibodies are also detected in 18% of the 1,124 deceased patients (aged 20 days-99 years; mean: 70 years). Moreover, another 1.3% of patients with critical COVID-19 and 0.9% of the deceased patients have auto-Abs neutralizing high concentrations of IFN-β. We also show, in a sample of 34,159 uninfected subjects from the general population, that auto-Abs neutralizing high concentrations of IFN-α and/or -ω are present in 0.18% of individuals between 18 and 69 years, 1.1% between 70 and 79 years, and 3.4% >80 years. Moreover, the proportion of subjects carrying auto-Abs neutralizing lower concentrations is greater in a subsample of 10,778 uninfected individuals: 1% of individuals <70 years, 2.3% between 70 and 80 years, and 6.3% >80 years. By contrast, auto-Abs neutralizing IFN-β do not become more frequent with age. Auto-Abs neutralizing type I IFNs predate SARS-CoV-2 infection and sharply increase in prevalence after the age of 70 years. They account for about 20% of both critical COVID-19 cases in the over-80s, and total fatal COVID-19 cases., (Copyright © 2021, American Association for the Advancement of Science.)

This paper investigates the electrochemical properties of a new Cu(II)-based metal-organic framework (MOF). Noted as Cu-YBDC, it is built upon a linker containing the propargyl carbamate functionality and immobilized on a glassy carbon electrode by drop-casting (GC/Cu-YBDC). Afterward, GC/Cu-YBDC was treated with HAuCl 4 and the direct electro-deposition of Au nanoparticles was carried at 0.05 V for 600 s (GC/Au/Cu-YBDC). The performance of both electrodes towards nitrite oxidation was tested and it was found that GC/Au/Cu-YBDC exhibited a better electrocatalytic behavior toward the oxidation of nitrite than GC/Cu-YBDC with enhanced catalytic currents and a reduced nitrite overpotential from 1.20 to 0.90 V. Additionally GC/Au/Cu-YBDC showed a low limit of detection (5.0 μM), an ultrafast response time (<2 s), and a wide linear range of up to 8 mM in neutral pH.

Background: Severe asthma in adolescents is a demanding challenge that deserves adequate management, including thorough work-up and rigorous follow-up., Methods: We evaluated a group of adolescents with severe asthma to investigate the change over time of clinical, functional, and biological parameters., Results: Most of adolescents treated with standard therapy improved, but some did not achieve an optimal asthma control and FeNO values increased., Conclusions: Despite guidelines-based therapy and clinical-functional improvement, type 2 inflammation could be not completely controlled. Biologics option could be considered if biomarkers suggest potential asthma relapse.

Infants affected by Heiner syndrome (HS) display chronic upper or lower respiratory tract infections, including otitis media or pneumonia. Clinically, gastrointestinal signs and symptoms, anemia, recurrent fever and failure to thrive can be also present. Chest X-rays can show patchy infiltrates miming pneumonia. Clinical manifestations usually disappear after a milk-free diet. The pathogenetic mechanism underlying HS remains unexplained, but the formation of immune complexes and the cell-mediated reaction have been proposed. Patients usually outgrow this hypersensitivity within a few years. The aim of this review is to provide an updated overview on the current evidence on HS in children, with a critical approach on the still undefined points of this interesting disease. Finally, we propose the first structured diagnostic approach for HS.

Inborn errors of immunity (IEI) are a heterogeneous group of disorders, mainly resulting from mutations in genes associated with immunoregulation and immune host defense. These disorders are characterized by different combinations of recurrent infections, autoimmunity, inflammatory manifestations, lymphoproliferation, and malignancy. Interestingly, it has been increasingly observed that common allergic symptoms also can represent the expression of an underlying immunodeficiency and/or immune dysregulation. Very high IgE levels, peripheral or organ-specific hypereosinophilia, usually combined with a variety of atopic symptoms, may sometimes be the epiphenomenon of a monogenic disease. Therefore, allergists should be aware that severe and/or therapy-resistant atopic disorders might be the main clinical phenotype of some IEI. This could pave the way to target therapies, leading to better quality of life and improved survival in affected patients., Competing Interests: The authors report no competing interests. The authors have no conflict of interest to disclose with respect to this study., (© 2021 The Author(s).)

Inborn errors of immunity (IEI) are a group of disorders that are mostly caused by genetic mutations affecting immune host defense and immune regulation. Although IEI present with a wide spectrum of clinical features, in about one third of them various degrees of gastrointestinal (GI) involvement have been described and for some IEI the GI manifestations represent the main and peculiar clinical feature. The microbiome plays critical roles in the education and function of the host's innate and adaptive immune system, and imbalances in microbiota-immunity interactions can contribute to intestinal pathogenesis. Microbial dysbiosis combined to the impairment of immunosurveillance and immune dysfunction in IEI, may favor mucosal permeability and lead to inflammation. Here we review how immune homeostasis between commensals and the host is established in the gut, and how these mechanisms can be disrupted in the context of primary immunodeficiencies. Additionally, we highlight key aspects of the first studies on gut microbiome in patients affected by IEI and discuss how gut microbiome could be harnessed as a therapeutic approach in these diseases.

Immune and inflammatory responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contribute to disease severity of coronavirus disease 2019 (COVID-19). However, the utility of specific immune-based biomarkers to predict clinical outcome remains elusive. Here, we analyzed levels of 66 soluble biomarkers in 175 Italian patients with COVID-19 ranging from mild/moderate to critical severity and assessed type I IFN-, type II IFN-, and NF-κB-dependent whole-blood transcriptional signatures. A broad inflammatory signature was observed, implicating activation of various immune and nonhematopoietic cell subsets. Discordance between IFN-α2a protein and IFNA2 transcript levels in blood suggests that type I IFNs during COVID-19 may be primarily produced by tissue-resident cells. Multivariable analysis of patients' first samples revealed 12 biomarkers (CCL2, IL-15, soluble ST2 [sST2], NGAL, sTNFRSF1A, ferritin, IL-6, S100A9, MMP-9, IL-2, sVEGFR1, IL-10) that when increased were independently associated with mortality. Multivariate analyses of longitudinal biomarker trajectories identified 8 of the aforementioned biomarkers (IL-15, IL-2, NGAL, CCL2, MMP-9, sTNFRSF1A, sST2, IL-10) and 2 additional biomarkers (lactoferrin, CXCL9) that were substantially associated with mortality when increased, while IL-1α was associated with mortality when decreased. Among these, sST2, sTNFRSF1A, IL-10, and IL-15 were consistently higher throughout the hospitalization in patients who died versus those who recovered, suggesting that these biomarkers may provide an early warning of eventual disease outcome.

Introduction: Chronic rhinosinusitis and asthma are heterogeneous diseases with complex pathogenesis. The presence of chronic rhinosinusitis with nasal polyps has been associated with increased asthma exacerbation frequency and may represent a predictor of future exacerbations in severe asthma., Areas Covered: This review provides the clinician with an overview of the prevalence and clinical impact of the chronic rhinosinusitis with nasal polyps in severe asthma and summarizes recommended therapeutic approaches, including innovative biologic therapies. To select relevant literature for inclusion in this review, we conducted a literature search using the PubMed and ClinicalTrials.gov databases, using terms 'chronic rhinosinusitis with nasal polyps' AND 'asthma' OR 'severe asthma.' The literature review was performed for publication years 2010-2020, restricting the articles to humans and English language publications., Expert Opinion: Biological therapies have opened new perspectives in the treatment of upper and lower airway allergic diseases. Care pathways in severe asthma are almost consolidated, while they still rely on phenotypic rather than endotypic features in chronic rhinosinusitis with nasal polyps. Unveiling the correlation between clinical phenotypes and molecular endotypes will allow better stratification of patients with chronic rhinosinusitis with nasal polyps to identify candidates who benefit most from biological therapy.

Allergic diseases have different frequencies. In particular, allergic rhinitis and asthma have high frequencies of about 20% and 10%, respectively. Other allergic diseases have lower frequencies; for example, food allergy has a frequency of 1%-4%. There are also rare allergic diseases, with a prevalence of 5 cases per 10 000 people in the general population, and they are included in Orphanet. However, other extremely rare allergic diseases still need to be properly known in order to be possibly recognized as rare diseases and cataloged in Orphanet., (© 2020 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Inborn errors of immunity (IEI), also referred to as primary immunodeficiencies (PID), are disorders that, for the most part, result from mutations in genes involved in immune host defense and immune regulation. Thanks to the increased availability of high-throughput DNA sequencing and the improvement in genomic data interpretation, the number of newly identified genes associated with IEI has exponentially increased over the last decade. We reviewed four recently described monogenic IEI and discussed the clinical and immunologic features of these new conditions., (© 2020 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

The prevalence, heterogeneity, and severity of type 2 inflammatory diseases, including asthma and atopic dermatitis, continue to rise, especially in children and adolescents. Type 2 inflammation is mediated by both innate and adaptive immune cells and sustained by a specific subset of cytokines, such as interleukin (IL)-4, IL-5,IL-13, and IgE. IL-4 and IL-13 are considered signature type 2 cytokines, as they both have a pivotal role in many of the pathobiologic changes featured in asthma and atopic dermatitis. Several biologics targeting IL-4, IL-5, and IL-13, as well as IgE, have been proposed to treat severe allergic disease in the pediatric population with promising results. A better definition of type 2 inflammatory pathways is essential to implement targeted therapeutic strategies., (© 2020 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

COVID-19 is a complex new viral disease, in which a strict balance between anti-viral immune response and the ensuing organ inflammation has a critical role in determining the clinical course. In adults, compelling evidence exists indicating that an uncontrolled inflammatory response ("cytokine storm") is pivotal in determining disease progression and mortality. Children may rarely present with severe disease. Modulating factors related to the host's genetic factors, age-related susceptibility, and the capability to mount appropriate immune responses might play a role in control virus load at an early stage and regulating the inflammatory reaction. Elucidating these mechanisms seems crucial in developing target therapies according to patient's age, immunologic status, and disease evolution in COVID-19., (© 2020 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Interindividual clinical variability in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is vast. We report that at least 101 of 987 patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia had neutralizing immunoglobulin G (IgG) autoantibodies (auto-Abs) against interferon-ω (IFN-ω) (13 patients), against the 13 types of IFN-α (36), or against both (52) at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 of the 101 were men. A B cell autoimmune phenocopy of inborn errors of type I IFN immunity accounts for life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Allergic diseases represent a global health burden. Patients with allergic diseases may experience disability, reduced quality of life and productivity, emotional distress, and social restrictions, especially in the most severe cases. Current advances in unveiling the pathogenesis of allergic disorders have paved the way for the development of novel therapeutic strategies. Biological drugs have been widely studied in pediatric allergic asthma, with strong evidence of efficacy and safety. Moreover, promising results derive from studies on other conditions such as atopic dermatitis, chronic spontaneous urticaria, and food allergy. This review analyzes recent evidence on the role of biologic therapies for allergic diseases, focusing on the pediatric age.

Inborn errors of immunity are diseases of the immune system resulting from mutations that alter the expression of encoded proteins or molecules. Total updated number of these disorders is currently 406, with 430 different identified gene defects involved. Studies of the underlying mechanisms have contributed in better understanding the pathophysiology of the diseases, but also the complexity of the biology of innate and adaptive immune system and its interaction with microbes. In this review we present and briefly discuss Inborn Errors of Immunity caused by defects in genes encoding for receptors and protein of cellular membrane, including cytokine receptors, T cell antigen receptor (TCR) complex, cellular surface receptors or receptors signaling causing predominantly antibody deficiencies, co-stimulatory receptors and others. These alterations impact many biological processes of immune-system cells, including development, proliferation, activation and down-regulation of the immunological response, and result in a variety of diseases that present with distinct clinical features or with overlapping signs and symptoms.

Eosinophilic esophagitis (EoE) is a chronic disease characterized by symptoms related to esophageal dysfunction and eosinophil-predominant inflammation (≥15 eosinophils/high power field). In the last ten years, several epidemiological studies showed a significant increase in the incidence and prevalence of EoE, especially in children in Western Countries. Although EoE often presents with gastrointestinal symptoms, adults and children may develop extraintestinal symptoms and behavioral issues. Also, the chronic nature of the disease, long-term therapies, and strict follow-up may impair the quality of life of patients and their family. This review summarizes current knowledge on the behavioral and psychosocial issues and quality of life of children and adolescents with EoE and their caregivers.

n December 2019, in Wuhan (Hubei, China), the first COVID-19 cases due to SARS-COV-2 had been reported. On July 1st 2020, more than 10.268.839 million people had developed the disease, with at least 506.064 deaths. At present, Italy is the third country considering the number of cases (n=240.760), after Spain, and the second for the cumulative number of deaths (n=249.271), after the United States. As regard pediatric COVID-19 cases, more than 4000 cases (have been reported; however, these figures are likely to be underestimated since they are influenced by the number of diagnostic tests carried out. Three pediatric deaths have been reported in Italy to date. We aimed to review the peculiar aspects of SARS-COV-2 infection in the pediatric population.

To date, the only disease-modifying treatment strategy for allergic rhinitis and asthma is allergen immunotherapy (AIT). There is evidence that AIT improves allergic rhinitis and asthma, such as reducing symptom severity and medication use and improving of quality of life, with a long-lasting effect after the end of the course. The recent clinical trials evidenced AIT effectiveness and safety in allergic asthma. Consequently, the current version of the GINA (Global Initiative for Asthma) guidelines recommend AIT as an add-on therapy for asthma. There is also evidence that AIT may exert preventive activity on the possible progression from allergic rhinitis to asthma in children and the onset of new sensitizations.

The control of asthma is the objective of asthma management. However, it is difficult to obtain in clinical practice. The Italian Society of Allergy and Clinical Immunology promoted the nationwide project "ControL'Asma" to investigate the real situation in a group of children and adolescents with asthma. The preliminary outcomes demonstrated that many asthmatic subjects do not achieve adequate asthma control. Moreover, asthma in Italian children and adolescents was usually more frequent in males, had an early onset and allergic phenotype with very frequent rhinitis comorbidity, uncontrolled and partly controlled asthma affected about the half of subjects. However, this project suggested that the assessment of asthma symptom perception by VAS could be a reliable tool in the asthma management.

Italy is one of the most exposed countries worldwide to COVID-19, and Lombardy is the most affected region in Italy. In this context, Fondazione IRCCS Policlinico San Matteo in Pavia, one of the largest University hospitals in the region, has been involved in the management of the outbreak since its inception. Immediately after the communication of the first Italian COVID-19+ patient, the Pediatric Unit has been completely reorganized to face the approaching outbreak. The optimization of the Pediatric Unit resources for COVID-19 emergency is reported as an example to safely preserve health activity during the pandemic.

Importance: The current rapid worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection justifies the global effort to identify effective preventive strategies and optimal medical management. While data are available for adult patients with coronavirus disease 2019 (COVID-19), limited reports have analyzed pediatric patients infected with SARS-CoV-2., Objective: To evaluate currently reported pediatric cases of SARS-CoV-2 infection., Evidence Review: An extensive search strategy was designed to retrieve all articles published from December 1, 2019, to March 3, 2020, by combining the terms coronavirus and coronavirus infection in several electronic databases (PubMed, Cochrane Library, and CINAHL), and following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Retrospective cross-sectional and case-control studies, case series and case reports, bulletins, and national reports about the pediatric SARS-CoV-2 infection were included. The risk of bias for eligible observational studies was assessed according to the Strengthening the Reporting of Observational Studies in Epidemiology reporting guideline., Findings: A total of 815 articles were identified. Eighteen studies with 1065 participants (444 patients were younger than 10 years, and 553 were aged 10 to 19 years) with confirmed SARS-CoV-2 infection were included in the final analysis. All articles reflected research performed in China, except for 1 clinical case in Singapore. Children at any age were mostly reported to have mild respiratory symptoms, namely fever, dry cough, and fatigue, or were asymptomatic. Bronchial thickening and ground-glass opacities were the main radiologic features, and these findings were also reported in asymptomatic patients. Among the included articles, there was only 1 case of severe COVID-19 infection, which occurred in a 13-month-old infant. No deaths were reported in children aged 0 to 9 years. Available data about therapies were limited., Conclusions and Relevance: To our knowledge, this is the first systematic review that assesses and summarizes clinical features and management of children with SARS-CoV-2 infection. The rapid spread of COVID-19 across the globe and the lack of European and US data on pediatric patients require further epidemiologic and clinical studies to identify possible preventive and therapeutic strategies.